Washington The National Academy of Sciences rejected Bush administration skepticism about global warming, declaring Wednesday that it was a real problem caused at least in part by man-made pollution that could well have a "serious adverse" impact by the end of the century.
The report of the prestigious academy came in response to a request by the White House seeking guidance about the conclusions of the UN's Intergovernmental Panel on Climate Change (IPCC), which have prompted calls for tough controls on greenhouse gas emissions.
"The (panel's) conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue," the report states. "Despite ... uncertainties, there is general agreement that the observed warming is real and particularly strong within the past 20 years."
The 24-page report acknowledges that some uncertainties remain about how much natural variation is contributing to global warming. But in general the report provides ammunition to European leaders and environmental groups who are demanding that President Bush support mandatory controls on the emissions of carbon dioxide and other greenhouse gases that scientists say trap heat in the atmosphere and contribute to the Earth's rising temperature.
Bush has rejected the mandatory controls contained in the 1997 Kyoto global warming agreement negotiated and signed by the U.S. and 167 countries, and hopes to unveil an alternative plan of voluntary targets before he departs next week for a meeting with European Union leaders in Gothenburg, Sweden.
"The report underscores ... the full measure of the vacuum in the administration's leadership on this issue," said Sen. John Kerry, D-Mass., a leading figure in the global warming debate.
The academy has previously reached similar conclusions about climate change and it was unclear why the administration went back to it on the same issue. White House officials wouldn't clarify their thinking late Wednesday, other than to say that the president's policy advisers had been eager to better understand what is certain and uncertain with regard to climate change.